One of the main reasons is that the quality of the terminal itself does not meet the requirements. The main problems are: the screw hole is too large, resulting in the reduction of the contact area of the terminal, and the fixing bolt is easy to loosen; The outer diameter of the terminal becomes thinner and the pipe wall becomes thinner; The depth in the pipe becomes shallower and the insertion part of the conductor becomes shorter; The length of copper in the copper aluminum transition part is shortened; The width of the contact surface part is reduced to reduce the contact area; The thickness of the contact surface is reduced

The second important reason is that the installation is not in place. For example, during the installation process, the wiring terminal and equipment clamp are not well connected, which is also one of the conditions to ensure safe power supply. After the fusing of the outdoor cable head wiring terminal, after careful inspection, it is found that there are melting points in the contact part between the lead clamp and the wiring terminal, This is also the corrosion caused by the contact between copper and aluminum, resulting in poor contact of the contact surface and overheating and burning loss

The third reason is that the load distribution is unreasonable. In other words, in the process of electric energy transmission, if the load of each phase is uneven, the load of one phase or two phases will be low and the load of the other phase or two phases will be high. The load current will be too large for a long time, which increases the failure probability of the cable line, accelerates the insulation aging, shortens the service life of the cable, and causes overheating damage to the external contact of the terminal head, The harm of cable overload is obvious

In addition to the above reasons, it is also necessary to consider the impact of lightning and other related factors. This is because in practical application, lightning strikes and line faults in summer are also another reason for the fusing of outdoor cable head terminals